目的  探讨外周血单个核细胞（PBMCs）中环状RNA（circRNA）在急性缺血性脑卒中（AIS）患者中的表达特征及其潜在生物功能，评估其在AIS诊断和预后中的临床价值。方法 在发现队列中对AIS患者（n=5）和健康对照者（n=5）的PBMCs样本进行全转录组测序，以获得AIS患者PBMCs来源的circRNA表达谱。选取前10个差异表达的circRNAs（DECs），通过功能富集分析探讨其潜在的调控机制。在验证队列（n=60）中使用Real-time PCR进行验证，筛选DECs，分析DECs在AIS临床诊断和预后评估中的价值。结果 在表达差异最大的前10个DECs中，基因本体论（GO）、京都基因和基因组百科全书（KEGG）通路分析显示，它们的宿主基因主要集中在免疫炎症反应、蛋白质降解和细胞死亡等过程。经Real-time PCR验证，两种circRNA，hsa_circ_0075436和hsa_circ_0005729，在AIS患者中显著下调。受试者工作特征（ROC）曲线分析显示hsa_circ_0075436和hsa_circ_0005729具有较高的诊断性能，且hsa_circ_0075436的表达水平与入院和出院时的美国国立卫生研究院卒中量表（NIHSS）评分成负相关，提示其与病情严重程度和预后相关。结论  DECs宿主基因参与了转录调控、蛋白泛素化及免疫、降解和凋亡等关键通路，其中hsa_circ_0075436 和 hsa_circ_0005729 可能是AIS诊断和预后的潜在生物标志物。

Objective To characterize the expression profiles and potential biological functions of circular RNAs (circRNAs) in peripheral blood mononuclear cells (PBMCs) from patients with acute ischemic stroke (AIS), and to evaluate their clinical relevance for diagnostic and prognostic applications. Methods Transcriptome-wide RNA sequencing was performed on PBMC samples collected from AIS patients (n=5) and age- and sex-matched healthy controls (n=5) in a discovery cohort to delineate the circRNA landscape in AIS. The top ten differentially expressed circRNAs (DECs) were identified based on fold change and statistical significance. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted to explore the biological functions of the host genes of these DECs. Validation of candidate circRNAs was performed using Real-time PCR in an independent validation cohort consisting of 30 AIS patients and matched controls. The diagnostic and prognostic significance of validated circRNAs was further assessed through correlation analyses with National Institutes of Health Stroke Scale (NIHSS) scores and receiver operating characteristic (ROC) curve analysis. Results  Functional enrichment analysis revealed that the host genes of the top DECs were predominantly involved in immune responses, protein degradation and cell death. Among the candidates, hsa_circ_0075436 and hsa_circ_0005729 were significantly downregulated in AIS patients as validated by Real-time PCR. Importantly, their expression levels were inversely correlated with NIHSS scores at both admission and discharge, suggesting a potential link to disease severity and neurological recovery. ROC analysis demonstrated that both circRNAs exhibited robust diagnostic performance, highlighting their potential as blood-based biomarkers. Conclusion The host genes of DECs are involved in key pathways related to transcriptional regulation, protein ubiquitination, immune response, protein degradation, and apoptosis. Among them, hsa_circ_0075436 and hsa_circ_0005729 represent promising candidates for further development as diagnostic and prognostic biomarkers in acute ischemic stroke.